According to the public information from TSMC on the new process node, it looks like we're in for significant power draw savings.

>Compared to its 10nm FinFET process, TSMC's 7nm FinFET features 1.6X logic density, ~20% speed improvement, and ~40% power reduction.

http://www.tsmc.com/english/dedicatedFoundry/technology/7nm....

Also, any speed increases due to redesign of the cores would be on top of the ~20% speed bump from the process node change.